Method and means for control of end-down servicing

ABSTRACT

In the end-down servicing of a spinning machine by an automatic yarn piecing apparatus, substantially all of the yarn retrieval step of each piecing operation is conducted during downstroke movement only of the ring rail of the spinning machine. Certain yarn-tensioning steps of each piecing operation, including the step of finally recommencing winding rotation of the bobbin at the spinning machine delivery undergoing servicing, are conducted only when the ring rail is moving upwardly and is adjacent the top of a reciprocatory stroke or traverse. In a preferred embodiment reversal of the direction of ring rail movement is sensed by a switching means including actuator and switch elements carried by the piecing apparatus for movement in unison with the ring rail of the spinning machine during part of each piecing operation except when the ring rail reverses its movement, at which time the switching means is actuated by relative movement between its components.

"United States Patent [191 Harmon et al.

[ METHOD AND MEANS FOR CONTROL OF END-DOWN SERVICING [75] Inventors: Albert D. Harmon, Clemson;

Charles R. Martin, Seneca; William H. Drake, Greenville, all of SC.

[73] Assignee: Saco-Lowell Corporation, Easley,

221 Filed: oa.23, 1973 2| Appl. No.: 408,780

{52] US. Cl 57/34 R; 57/345; 57/l56 [5 l] Int. Cl. D01" 15/00 [58] Field of Search 57/22, 34 R, 34 'TT, 34.5, 57/52, 53, 54, 107, Ill, I56; 242/355 R, 35.6 E

[56] References Cited UNITED STATES PATENTS 3,128,590 4/1964 Escursell-Prat 57/34.5 X 3,373,55l 3/1968 Gillono et al. 57/34 R 3,664,109 5/!972 Escursell-Prat.. 57/34 R 3,807,l55 4/[974 Miyazaki et al.. 57/34 R 3,827,226 8/1974 Lesser v 57/34 R [4 1 Sept. 16, 1975 Primary Examiner-Donald E. Watkins Attorney, Agent, or FirmJoseph H. Heard ABSTRACT In the end-down servicing of a spinning machine by an automatic yarn piecing apparatus. substantially all of the yarn retrieval step of each piecing operation is conducted during downstroke movement only of the ring rail of the spinning machine. Certain yarntensioning steps of each piecing operation, including the step of finally recommencing Winding rotation of the bobbin at the spinning machine delivery undergoing servicing, are conducted only when the ring rail is moving upwardly and is adjacent the top of a reciprocatory stroke or traverse. In a preferred embodiment reversal of the direction of ring rail movement is sensed by a switching means including actuator and switch elements Carried by the piecing apparatus for movement in unison with the ring rail of the spinning machine during part of each piecing operation except when the ring rail reverses its movement, at which time the switching means is actuated by relative movement between its components.

18 Claims, 6 Drawing Figures METHOD AND MEANS FOR CONTROL OF END-DOWN SERVICING BACKGROUND OF THE INVENTION This invention relates to the end-down servicing of textile spinning machines by automatic yarn piecing apparatuses, and is particularly but not necessarily exclusively applicable to an apparatus which during a piecing operation retrieves a length of previously spun yarn from the bobbin-yarn package at the spinning machine delivary undergoing end-down servicing, and thereafter joins such yarn with roving issuing from the drafting rolls of the spinning machine at such delivery. Illustrative piecing apparatuses of the foregoing general type are disclosed in US. Pat. Nos. Re. 26,230, 3,712,040, and 3,728,852.

A piecing apparatus of the aforesaid type normally includes a wheeled carriage movable adjacent one or more spinning machines to a delivery thereof requiring servicing by reason of an end-down, or broken yarn, condition thereat. Upon detection of such a delivery, the apparatus halts in front of it and commences a piecing operation. In accordance with a preferred piecing technique, one of the first steps performed by the apparatus is retrieval of a length of previously spun yarn from the bobbin-yarn package at the machine delivery undergoing servicing. Yarn retrieval is normally accomplished by applying suction and/or beating forces to the surface of the bobbin-yarn package immediately above the spinning ring encircling such package and carried by a vertically reciprocating ring rail of the spinning machine, while rotating the package in an unwinding direction. During the yarn retrieval step, the suction head, beater and/or other yarn retrieving components of the apparatus are supported by or connected to the ring rail of the spinning machine for vertical movement in unison with it. Following retrieval of a length of yarn from the bobbin-yam package, the piecing apparatus proceeds with other steps of the piecing operation. These customarily include, among other possible steps, threading the retrieved yarn with the traveler movable about the spinning ring encircling the package, and joining the retrieved and travelerthreaded yarn to the roving issuing from the draft rolls of the spinning machine at the delivery undergoing servicing, to re-establish the continuous thread-line" between such drafting rolls and the bobbin-yam package. Rotation of the package is recommenced at approximately the time of re-establishment of the thread-line, which is normally the last step in a piecing operation.

In the prior art piecing apparatuses, there has in most instances been no correlation between the times at which various steps of each piecing operation are performed and the position or direction of movement at such times of the ring rail of the spinning machine at the delivery undergoing servicing. The location and/or direction of movement of the ring rail at the time of performance of any particular step of a particular piecing operation has generally been purely a matter of chance, and therefore has varied randomly from piecing operation to piecing operation. An exception to the foregoing conventional practice is set forth in 0.5. Pat. No. 3,641,758, which disclosed means associated with a piecing apparatus for detecting the reciprocatory position of the ring rail of the spinning machine and for initiating the yarn retrieving step of each piecing operation when the ring rail is at a predetermined desired location within a reciprocatory traverse or stroke. In the preferred embodiment of the invention disclosed in such patent, yarn retrieval is commenced when the ring rail is closely adjacent the bottom of a downward stroke and is continued, irrespective of possible reversal of the direction of ring rail movement in the meantime, for either a predetermined time interval or until the retrieval of a desired length of the yarn is detected by photoelectric or other means. The reasons set forth in the patent for the aforesaid preferred mode of operation are: (l) to insure the withdrawal of a segment of yarn of the desired length, and/or (2) to minimize the time-period during which yarn on the package is subject to the possibly-deteriorating effect of the yarn retrieving means.

It has now been deter-mined that, for reasons difi'erent from those noted above, the efficiency and reliability of operation of an automatic yarn piecing apparatus can be significantly improved if, during each piecing operation, substantially all of the yarn retrieval step is conducted only during downward movement of the ring rail of the spinning machine, and not in any significant part during upward ring rail movement. In the latter connection, it has been noted that when yarn retrieval forces are applied to the surface of the bobbinyam package while the ring rail and the yarn retrieval means are moving upwardly relative to such package, snarling or tangling of the yarn frequently ensues. Apparently the yarn retrieval forces then include a component which is directed upwardly, that is in the axial direction of the small diameter portion of the tapered chase surface of the package, and which so loosens and/or displaces the yarn coils upon the package as to permit them to entangle with adjacent coils or adjacent components of the piecing apparatus or spinning machine. The resulting snarl or tangle may not only prevent successful completion of the piecing operation then in progress, but moreover may preclude automatic repair of the end-down condition during subsequent piecing attempts. If substantially all of the yarn retrieval step is conducted during downstroke movement of the ring rail, on the other hand, the coils of yarn upon the package are less likely to be undesirably loosened or displaced by the axial component of the yarn retrieving forces exerted thereon, since such force component is in the downward direction of the larger diameter end of the chase surface of the package. Snarling or tangling of the yarn during attempted retrieval thereof is therefore much less likely to ensue.

Another problem heretofore adversely affecting the reliability and efficiency of automatic piercing operations has been that of inadvertent breakage of the yarn following traveler threading thereof and when substantial tension is imparted to it by the performance of a subsequent step in the piecing cycle. While different piecing techniques may include different steps which tension the traveler threaded yarn, a major one common to virtually all piecing operations is the recommencing of winding rotation of the bobbin-yarn package. Depending upon the particular piecing apparatus and technique employed, this step may be performed concurrently with, immediately after, or immediately prior to re-establishment of the thread-line between the bobbin-yam package and the drafting rolls of the spinning machine delivery undergoing servicing. Whatever might be the precise time at which this or other tensioninducing steps are performed, it has been noted that yarn breakage is particularly likely to result therefrom if the ring rail of the spinning machine is then adjacent the bottom of a reciprocatory stroke or traverse. The reason for this phenomena is believed to be as follows. Once a traveler threaded length of yarn has been established by the piecing apparatus, an included angle of some magnitude is defined between the first and second sections of such yarn which respectively extend to the traveler from the bobbin-yam package, and upwardly from the traveler toward the elevation of the drafting rolls of the spinning machine. Downward movement of the ring rail decreases the magnitude of such included angle, and also tends to tension the yarn. Upward movement of the ring rail increases the in cluded angle, and tends to slacken the yarn. The likelihood of the yarn being in a slackened condition capable of withstanding breakage upon the imposition of tension thereon, by the performance of a step of the piecing operation is therefore greatest when the ring rail is adjacent the top of a traverse and least when the ring rail is adjacent the bottom of a traverse. The foregoing is true even in the case of a yarn-tensioning operational step other than that of recommencing winding rotation of the bobbin-yam package. If the latter step is performed when the ring rail is adjacent the bottom of a traverse, the possibility of yarn breakage is particularly great. The minimal angle then defined between the sections of the yarn extending to and from the traveler produces a maximum snubbing effect" upon it. Yarn breakage is therefore likely to occur before ten sion-relieving movement of the traveler about the spinning ring upon which it is mounted. On the other hand, when package rotation is resumed when the ring rail is adjacent the top of a reciprocating stroke, the included yarn angle at the traveler, and the latters freedom for movement about the spinning ring, are at a maximum. The possibility of the yarn being in a slackened condition is then also greatest. Due to one or both of the aforesaid factors, recommencement of package rotation is much less likely to cause yarn breakage.

OBJECTS OF THE INVENTION Primary objects of the invention are to improve the reliability and efficiency of automatic yarn piecing operations by decreasing the possibility of yarn snarling or entanglement during retrieval of a length of yarn from a bobbin-yam package of a spinning machine delivery undergoing end-down servicing, and/or by decreasing the possibility of breakage of traveler-threaded yarn during the performance in a piecing operation of a step or steps which tend to significantly tension such yarn.

Related and more specific objects are the provision of a method and means, in association with an automatic yarn piecing apparatus, whereby the step of retrieving yarn from the bobbin-yam package at the machine delivery undergoing servicing is conducted in significant part only during downward movement of the ring rail of the spinning machine; and/or whereby, following the establishment of a traveler-threaded length of yarn extended between the bobbin-yam package of a spinning machine undergoing servicing and an elevation adjacent the machines drafting rolls, the step of recommencing package rotation, and preferably any other steps of the piecing operation which impose appreciable tension upon the length of traveler-threaded yarn, are so performed only while the ring rail of the spinning machine approaches the top of a reciprocatory stroke or traverse thereof, i.e., is moving upward.

Another related and more specific object is the provision, in association with an automatic yarn piecing apparatus, of improved means for detecting the position of the ring rail of the spinning machine at the machine delivery undergoing end-down servicing by the apparatus, the improved detecting means preferably being responsive to reversals of the direction of movement of a ring-rail at both ends of a reciprocatory stroke or traverse, and in no way impeding movement of the piecing apparatus, if desired, between opposite sides of a spinning machine or from one spinning machine to another.

SUMMARY OF THE INVENTION The present invention provides, in the end-down servicing by an automatic yarn piecing apparatus of a textile spinning machine having a ring rail reciprocatorily movable axially of an upstanding bobbin-yam package which during a piecing operation extends through the ring rail and is adapted to have a length of yarn retrieved from it, an improved method and means whereby substantially all of the step of retrieving yarn from the package is conducted during downward movement only of the ring rail of the spinning machine. The invention further provides, in accordance with another aspect of it and in association with an automatic yarn piecing operation which includes the step of establishing a traveler-threaded length of yarn extending at one end to the bobbin or other package at the spinning machine delivery undergoing end-down servicing and extending at its other end upwardly toward the elevation of the drafting rolls at such delivery, for the performance of remaining operational steps which tend to substantially tension the yarn, such as the step of recommencing winding rotation of the package, only when the ring rail of the spinning machine approaches the top of a reciprocatory stroke or traverse which is to say on its upstroke.

In a preferred embodiment of the invention, detection of the direction of movement and position of the ring rail of a spinning machine are achieved by sensing reversal of the direction of ring rail movement at both ends of its reciprocatory strokes. Yarn retrieval is commenced in response to detected reversal of the direction of ring rail movement from up to down, and is terminated in response to detected reversal of ring rail movement from down to up. Remaining steps of the piecing operation are conducted in timed relationship to the aforesaid detected reversal of ring rail movement from down to up, so that the major yam-tensioning one or ones of such steps are performed while the ring rail is moving towards the top of an upstroke, or has reached the top of the upstroke.

The present invention also provides, in association with an automatic yarn piecing apparatus servicing one or more spinning machines having reciprocatorily movable ring rails on opposite sides thereof, improved means for detecting the position and/or direction of movement of the ring rail at each machine delivery serviced by the apparatus. The detecting means is of economical, durable and highly reliable construction. In its preferred form, the detecting means senses reversal of movement of a ring rail at both ends of a reciprocatory stroke thereof, and is so mounted and arranged as to in no way impede free movement of the piecing apparams from one side of a spinning machine to the other, or to another spinning machine, if desired.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and benefits of the invention will be in part apparent and in part pointed out hereinafter in the following description of an illustrative embodiment thereof, which should be read in conjunction with the accompanying drawings, in which:

FIG. 1 is a fragmentary and somewhat schematic side elevational view, partially in vertical section, of a bobbin-yarn package encircled by the rail-mounted spinning ring at a delivery of a textile spinning machine, and of the yarn retrieval means and certain adjacent components of an automatic yarn piecing apparatus servicing such machine delivery;

FIG. 2 is a view similar to FIG. 1 of a bobbin-yarn package and related spinning machine components such as shown in FIG. 1, following traveler-threading of a length of yarn extending at one end to the bobbinyarn package and its other end extending upwardly toward the elevation of the drafting rolls of the spinning machine;

FIG. 3 is a fragmentary and somewhat schematic elevational view, partially in vertical section taken approximately along the line 33 of FIG. 1, showing switching means of the piecing apparatus for detecting the position and/or direction of movement of the ring rail of the spinning machine at the delivery thereof undergoing servicing by the apparatus, the components of the switching means being shown in their relative positions occupied during downward movement of the ring rail;

FIG. 4 is an elevational view similar to FIG. 3, but showing the components of the switching means in their relative positions occupied during upward ring rail movement;

FIG. 5 is an exploded, fragmentary perspective view of the switching means shown in FIGS. 3 and 4; and

FIG. 6 is a diagrammatic view of electrical control circuitry associated with the switching means of FIGS. 35.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 the numerals 10 and 12 respectively designate a textile spinning machine and an automatic yarn piecing apparatus, only fragmentary parts of which are shown. Spinning machine 10 may be of a conventional and well-known type including, on each side thereof, a stationary spindle rail (not shown) and a vertically movable ring rail 14 which extend parallel to one another longitudinally of the machine and have a plurality of yarn spinning stations or deliveries spaced along the length thereof. At each delivery of machine 10, yarn (which term is intended to encompass roving) issuing from the machines drafting rolls (not shown) normally extends downwardly through suitable guides (not shown) to and through a traveler 16 movable about a spinning ring 18 carried by ring rail 14, and thence to a bobbin-yarn package 20 encircled by ring 18 and mounted upon the spinning machines spindle rail (not shown) for rotation about a substantially vertical axis. During normal operation of the machine 10, package 20 is rotated about its axis so as to cause the yarn to be wound thereon, while ring rail 14 is moved vertically through reciprocatory strokes or traverses so as to cause the package to possess the desired charac teristics or build". When the package 20 being formed is of the filling-wind type shown in FIGS. 1 and 2, ring rail 14 may reciprocate through a constant traverse or stroke of, say, approximately two inches as it is moved slowly from a lowermost and to an uppermost position relative to the bobbin component of the package. Ring rail 14 is shown in FIG. 1 approximately two-thirds of the way through a downward traverse or stroke, as is indicated by the directional arrow and by the rails position relative to the upper and lower extremities of the sloping chase-surface of bobbin-yarn package 20.

Piecing apparatus 12 may be and illustratively is of the general type disclosed in US. Pat. Nos. 3,651,628, 3,712,040 and 3,728,852. Such an apparatus includes a carriage movable adjacent one or more spinning machines to a delivery thereof requiring servicing by reason of an end-down (broken yarn) condition thereat. Upon arriving at such a delivery, the carriage of the apparatus is halted and various servicing assemblies carried by and extendable from it perform sequential steps of a piecing operation which eliminates the yarn discontinuity and thereby again places the spinning machine delivery in production. Each piecing operation performed by such apparatus includes, among other steps, that of retrieveing a length of yarn from the bobbin-yarn machine at the spinning machine delivery undergoing servicing. FIG. 1 shows, in fragmentary and partially schematic form, a servicing assembly 22 which includes components for performing the yarn retrieval step. Assembly 22 is of the known construction disclosed in US. Pat. No. 3,728,852 and including a suction head 26, a beater 24, and a ball spline 28. An extendable and retractable support arm 30 is connected to ball spline bushing 28. Bushing 28 mounts assembly 22 and arm 30 for vertical movement along an elongate splined shaft 32 of apparatus 12, and the center section of the bushing further mounts assembly 22 for pivotal movement about the axis of shaft 32. Assembly 22 and support arm 30 normally occupy elevated and rearwardly (to the right, as viewed in FIG. 1) retracted rest positions, so as to then in no way impede movement of the carriage of apparatus 12 to any delivery of a spinning machine 10 serviced thereby. After apparatus 12 has halted at a machine delivery requiring end-down servicing, assembly 22 descends upon shaft 32 and support arm 30 extends forwardly from apparatus 12 so as to engage ring rail 14 of machine 10 and support assembly 22 for vertical recipro catory movement in unison therewith. Thereafter, and as is shown in FIG. 1, suction head 26 and beater 24 are actuated and are pivoted forwardly about the axis of shaft 32 so as to exert yam-retrieving suction and beating forces upon the chase surface of bobbin-yarn package 20 while such a package is rotated in an unwinding direction by another mechanism (not shown) of piecing apparatus 12. If the yarn retrieving step is successful, this causes yarn previously wound upon package 20 to be withdrawn therefrom and sucked into suction head 26. Assembly 22 is then pivoted rearwardly away from package 20, and rotation of the package is halted. A traveler-threading mechanism (not shown) of apparatus 12 then interconnects the retrieved yarn and the traveler 16 mounted upon the spinning ring 18 encircling package 20, after which the retrieved and traveler-threaded length of yarn is extended upwardly as shown in FIG. 2 toward the elevation of the drafting rolls (not shown) of spinning machine 10 by return upward movement of assembly 22 to its elevated rest" position upon spline shaft 32. Upon return movement of assembly 22 to its aforesaid position, support arm 30 is returned to a retracted position. Another servicing assembly, which is not shown in the drawings but which may be of the general type disclosed in U.S. Pat. No. 3,712,040, then interconnects the retrieved and traveler threaded yarn with roving issuing from drafting rolls (not shown) of spinning machine 10, thereby reestablishing the desired thread-line between such drafting rolls and package 20. When the latter result is effected by the servicing assembly and procedure disclosed in US. Pat. No. 3,712,040, winding rotation of the package is recommenced after the upper end of the yarn has been clamped and moved forwardly and upwardly along an arcuate path of travel toward the drafting rolls (not shown) of machine 10, and shortly before the yarn is brought into engagement with roving issuing from such drafting rolls. Substantial tension tends to be imposed upon the yarn first by the upward movement of its clamped upper end along the aforesaid arcuate path of travel, and thereafter by the recommencing of winding rotation of package 20. If a different mechanism and/or technique is employed for joining a traveler-threaded length of yarn with roving issuing from the drafting rolls of a spinning machine undergoing end-down servicing, winding rotation of the bobbin at the machine delivery undergoing surfacing will still be recommenced at approximately the time of reestablishment of the thread-line between such package and the drafting rolls of the spinning machine, and such step, and possibly at least one more preceding it, will tend to impose substantial tension upon the travelerthreaded yarn.

For reasons most apparent from FIG. 2, to which reference is now made, breakage of the traveler-threaded yarn is most likely to ensue if the aforesaid yarntensioning step or steps are performed while ring rail 14 is adjacent the bottom of a reciprocatory traverse, and is least likely to ensue if such step or steps are per formed when ring rail 14 is adjacent the top of a reciprocatory traverse. Following the establishment during a piecing operation of a traveler-threaded length of yarn having a first section extending from a package 20 to traveler l6, and a second section extending upwardly from traveler 16 toward the drafting roll elevation of spinning machine 10, an included angle A (FIG. 2) is defined between such yarn sections. Irrespective of the original magnitude of angle A, downward movement of ring rail 14 decreases it and at the same time tends to increase the tension in the yarn, while upward movement of ring rail 14 increases the magnitude of angle A and tends to slacken the yarn. The likelihood of the yarn being in a slackened condition capable of withstanding breakage upon the performance of a yarn tensioning step of the piecing operation, such as the previously-noted step of moving the clamped upper end of the yarn upwardly along an arcuate path of travel toward the drafting rolls (not shown) of machine 10, is therefore greatest when ring rail 14 is adjacent the top of a reciprocatory traverse and is least when ring rail 14 is adjacent the bottom of a traverse. When the yarn-tensioning step is that of recommencing winding rotation of package 20, breakage of the yarn is particularly likely to occur if such step is performed when ring rail 14 is adjacent the bottom of a traverse. In addition to the yarn possibly being in a maximum pretensioned condition, a maximum snubbing effect" is then exerted by the yarn upon traveler 16 due to angle A then being of minimal magnitude. When winding rotation of package 20 is recommenced when ring rail 14 is adjacent the top of a reciprocatory traverse, on the other hand both the slackened condition of the yarn and the magnitude of angle A tend to be at a maximum. Breakage of the yarn is much less likely to ensue. In accordance with the present invention, therefore, during each piecing operation performed by apparatus 12 the step of recomrnencing winding rotation of package 20, and preferably any other step tending to impose substantial tension upon the traveler-threaded yarn, is performed only when ring rail 14 of machine 10 is approaching or adjacent the top of a reciprocatory traverse, which traverse is preferably an upward one adjacent the sloped package chase.

In connection with another aspect of the invention, and referring now particularly to FIG. 1, it has been noted that when yarn retrieving forces are applied to package 20 while ring rail 14 and the yarn-retrieving component or components of apparatus 12 are moving upwardly relative to such package, the likelihood of the yarn snarling or tangling is much greater than when substantially all of the yarn retrieving step is performed while ring rail 14 and the yarn retrieving component or components of apparatus 12 are moving downwardly. Pursuant to the present invention, therefore, substantially all of the yarn retrieving step of each piecing operation is performed only when ring rail 14 is moving downwardly. Preferably the yarn retrieving step of each piecing operation is initiated when ring rail 14 undergoes a reversal of the direction of its movement from upwardly to downwardly, and it terminated when ring rail 14 undergoes the next reversal of the direction of its movement, from downwardly to upwardly. While such procedure might appear to cause the retrieval an extremely short section of yarn at a spinning machine delivery where the free yarn end is disposed upon a lower part of the chase surface of the package 20, the effect of the yarn end being so located is offset somewhat by the larger diameter of the package chase surface adjacent its lower end. If the retrieval of yarn sections of varying lengths presents a problem, it would also of course be possible to provide photoelectric or other means, such as disclosed in US. Pat. No. 3,728,550 but in association with means for in any event terminating the yarn piecing step at the time indicated herein, for terminating such step at an earlier time in the downward movement of ring rail 14 in response to the detected retrieval of a section of yarn of a desired length.

The additional control means provided upon apparatus 12, for correlating one or more operational steps of each piecing operation with the position and/or direction of movement of the ring rail 14 at the spinning machine delivery undergoing servicing, may be and preferably is of an improved type not requiring the permanent connection of any component to either ring rail of the spinning machine and not impeding free movement of apparatus 12 from one side of a spinning machine to the other. or to another spinning machine, if desired.

Referring first particularly to FIGS. 3-5, the improved control means comprises switching means including a switch element 36 and a switch-actuator element 38; means mounting one of said switching elements, illustratively switch element 36, for movement at desired times in unison with the ring rail 14 of a spinning machine 10 undergoing servicing by piecing apparatus 12; and means mounting the other of said switching elements, illustrating actuator element 38, for movement in unison with switch element 36 except upon reversal of the direction of movement of switch. element 36, at which time relative movement between elements 36, 38 ensues and causes actuation of switch element 36. Switch element 36 is fixedly mounted upon a bracket plate 40 secured to the non-rotating upper portion of the bushing 28 movable vertically of splined shaft 32 and supported as previously described, during part of each piecing operation, by arm 30 (FIG. I) for vertical reciprocatory movement in unison with ring rail 14. A movable switch arm 42, carrying a roller 44 at its outer end, projects angularly downwardly from the main body of switch element 36 and is biased toward a wall panel (or any other suitable part) of the carriage of apparatus 12 extending in spaced parallel relationship to splined shaft 32. A vertically extending strip of magnetized material 46, having a length approximately equal to that of splined shaft 32 is bonded or otherwise permanently affixed to the aforesaid wall panel of apparatus 12. A slide member 48, which is formed of magnetically-attractable metal or other material overlies strip 46 and is magnetically held against it. Upon the exertion upon member 48 of a vertical displacing force of sufficient magnitude to overcome the magnetic-drag forces to which it is subject, member 48 slides vertically along strip 46. Approximately midway the length of its main body portion, slide member 48 has a bifurcated portion 48' extending horizontally therefrom toward switch element 36 and through a horizontally extending slot 50 provided within a transversely-bent flange 40' of the bracket plate 40 supporting switch element 36. Actuator element 38 comprises a block of wear-resistant plastic material, such as nyion, having a vertically-inclined cam surface 52 upon its forward face, and a pair of horizontally extending slots 54 upon its opposite sides. Slots 54 receive bifurcated portion 48' of slide member 48 and mount actuator element in a position wherein its cam surface 52 is engaged by roller 44 of switch element 36. The thickness of bifurcated portion 48' of slide member 48 is less than the vertical dimension of the slot 50 within switch mounting plate 40, and also is preferably slightly less than the vertical dimension of the slots 54 within actuator element 52. The aforesaid clearances, and particularly the former one, provides a desired capability for lost motion and limited relative movement between elements 36, 38.

The operation of the aforesaid switching means can best be understood by comparing the different relative position occupied by its components in FIGS 3 and 4. FIG. 3 illustrates the switching components as they appear when, as shown in FIG. I, arm 30 supports bushing 28 upon ring rail I4 of a spinning machine 10 being serviced by apparatus i2, and rail 14 is moving downwardly in one of its reciprocatory traverses. Due to their affixed interconnection with bushing 28, plate 40 and switch element 36 are moving downwardly in unison with ring rail 14. Slide member 48 is also being moved downwardly in unison with ring rail 14 due to engagement of the upper edge of slot 50 of plate 40 with the upper surface of bifurcated portion 48' of slide member 48. Actuator element 38 is, in turn, also moving downwardly in unison with ring rail 14 due to engagement between the confronting undersurfaces of bifurcated portion 48' of slide member 48 and slots 54 of element 38. A clearance or spacing is present between the undersurface of bifurcated portion 48' of slide member 48 and the lower edge of slot 50 of plate 40, and a smaller clearance or spacing may also be present between the confronting upper surfaces of portion 48 of member 48 and slots 54 of actuator element 38. The roller 44 upon arm 42 of switch element 36 engages a lower and relatively distal portion of the sloping cam surface 52 of actuator element 38, and arm 42 is biased to a rightward position.

The aforesaid relationship between the switching components is maintained until ring rail 14 reverses the direction of its movement at the end of its downstroke, and commences moving upwardly. At the instant ring rail 14 commences upward movement, bushing 28, plate 40 and switch element 36 also immediately commence upward movement in unison with the ring rail. However, actuator element 38 remains stationary until the lower edge of slot 50 of plate 40 engages the undersurface of portion 48' of slide member 48, and until the upper surface of portion 48' of member 48 engages the upper surfaces of slots 54 of element 38. During and as a consequence of the aforesaid relative movement between switch element 36 and actuator element 38, which relative movement transpires within a fraction of a second, roller 44 of switch 36 rides upwardly upon the sloping cam surface 52 of element 38, causing switch-actuating displacement of switch arm 42 to a leftward position. The new relative positions occupied by the components of the switching means, following the aforesaid actuation of switch element 36 and the recommencement of movement of actuator element 38 in unison with switch element 36, are shown in FIG. 4.

The FIG. 4 positional relationships between the switching components remains substantially constant as they move upwardly in unison with ring rail 14 of spinning machine 10, and until ring rail 14 reverses the direction of its movement at the top of its reciprocatory traverse. When this occurs relative movement between switch element 36 and actuator element 38 again transpires, such that the components are restored to their relative positions shown in FIG. 3, and switch element 36 is actuated by biased return movement of its arm 42 back to the right. It will therefore be apparent that whenever arm 30 (FIG. 1) supports bushing 28 for movement in unison with a ring rail 14 of a spinning machine 10, switch 36 will be actuated in first direction upon reversal of the direction of movement of such ring rail at the bottom of each reciprocatory stroke thereof, and switch 36 will be actuated in a second direction upon reversal of the direction of movement of ring rail at the top of each reciprocatory stroke.

The aforesaid capability for switch-actuating relative movement between elements 36, 38 is realized primarily by the lost-motion clearance or spacing provided between portion 48' of slide member 48 and the upper and lower edges of slot 50 of switch mounting plate 40. The smaller clearance of spacing between portion 48' of member 48 and the upper and lower surfaces of slots 54 of actuator element 38, which clearance is shown on a somewhat exaggerated scale in the drawings for purposes of clarity, is provided primarily to prevent inadvertent actuation of switch element 36 due to machine vibration and the like.

Referring now to the electrical control circuitry diagrammatically shown in FIG. 6, switch element 36 engages its down contact36' when switch arm 42 is in its rightward position shown in FIG. 3, and engages its up" contact 36" when switch arm 42 is in its leftward position shown in FIG. 4. In addition to the aforesaid components, the FIG. 6 electrical circuitry includes switch elements 56, 58 and 60; flip flop circuits 62, 64; capacitors 66, 68 and 70 with associated pull up resistors; and nand gates 72, 74, 76, 78, 80 and 82. The output of gate 82 is directed to the clutch circuitry of the main control cam shaft (not shown) of apparatus 12 and a high ouput pulse from gate 82 effects rotation of the cam shift. Among the cams upon such shaft are ones controlling pivotal movement of assembly 22 (FIG. 1) about the axis of splined shaft 32 and controlling the means (not shown) for rotating beater 24 and producing a suction air-flow through suction head 26. Additional cams upon the shaft include one for actuating the switch 60 shown in FIG. 6, and others for causing the performance in programmed sequence of steps of each operation following the yarn retrieval step. The illustrated positions of switches 36, 56, 58 and 60 are those occupied prior to the commencement by apparatus 12 of a piecing operation. Since switch 60 is open, the input from gate 76 to gate 80 is low, and the input from gate 80 to gate 82 is therefore high. The input from gate 78 to gate 82 is maintained high, irrespective of the position of switch 36, since flip flop 62 has a low output, which inhibits gate 78, when switches 56, 58 are in their illustrated positions. Switches 56, 58 are operable in response to movement of assembly 22 (FIG. I) to and from its elevated rest position, as by components of a cable assembly (not shown, but as disclosed in US. Pat. No. 3,728,852) associated with assembly 22 for permitting or causing its movement along splined shaft 32 (FIGS. 13) between its elevated position and the elevation of a ring rail 14 of spinning machine serviced by apparatus 12.

After apparatus 12 has halted at a spinning machine delivery requiring servicing, and assembly 22 has descended from its elevated rest" position to a position of supported engagement through arm 30 with the ring rail 14 at such delivery, switch 58 closes and flip flop 62 directs an inhibition-releasing high pulse to gate 78. Assuming that ring rail 14 is moving downwardly when switch 58 closes, the first change thereafter occuring in the position of switch 36 will transpire when ring rail 14 reverses its movement at the end of a traverse from downwardly to upwardly, at which time contact 36 will open and contact 36" will close. This causes flip flop 64 to direct an inconsequential high pulse to capacitor 66, and a low pulse to capacitor 68. The resulting discharge of capacitor 68 causes the gate 80 to receive a high pulse from gate 74, but this also is of no consequence due to the inhibited condition of gate 80. The next change in condition of switch 36, which would also be the first change if ring rail 14 were moving upwardly at the same time switch 58 closed, occurs when ring rail 14 reaches the top of its traverse and reverses movement from upwardly to downwardly. This closes switch contact 36' and opens contact 36", which changes the output from flip flop 64 to capacitor 66 from high to low. The ensuing discharge of capacitor 66 and production by gate 72 of a second high input at gate 78 produces a low input pulse and a high output pulse at gate 82. In response to the high pulse from gate 82, the control cam shaft (not shown) of apparatus 12 rotates sufiiciently to initiate the yarn retrieving step of the piecing operation. The limited rotation of the cam shaft also causes switch to close, thereby causing gate 76 to direct an inhibition releasing high pulse to gate 80. Yarn retrieval continues, if not earlier terminated, throughout the downstroke of ring rail 14 and until reversal of its movement from downwardly to upwardly. This causes movement of switch 36 from contact 36' to contact 36" and thereby produces, through the intervening circuit components, low input pulses and another high output pulse at gate 82. The rotation of the control cam shaft (not shown) initiated by this second high pulse from gate 82 immediately terminates the yarn retrieval step of the piecing operation, assuming again that such step has not been earlier terminated, and thereafter causes the remaining operational steps to be performed in predetermined timed sequence. The program-sequence of the cam shaft is so correlated to the traverse speed of ring rail 14 that at least the step of recommencing winding rotation of bobbin-yam package 20, and preferably all other steps tending to impose substantial tension upon the traveler threaded yarn extending to such package, are performed only when ring rail 14 is rising toward or at the top of a reciprocatory traverse. Preferably the rising ring rail treverse adjacent the top when the yarn tensioning step is performed and is the upward traverse immediately following the downward one during which yarn retrieval transpires, since this permits completion of each piecing operation in minimal time. If apparatus 12 is of a type adapted to perform a second piecing operation upon detected failure of a first one at a delivery undergoing servicing, the aforesaid preferred timing also preserves the possibility of the yarn retrieving step of the second operation being conducted without delay during the next ensuing downward traverse of ring rail 14 Following the yarn retrieving step of each piecing operation, rotation of the cam shaft (not shown) of apparatus l2 and return movement of assembly 22 (FIG. 1) to its elevated position restores the switches of the FIG. 6 circuitry to their illustrated conditions. Apparatus 12 is therefore ready for the performance of a piecing operation at another delivery requiring servicing, when required. Apparatus 12 may move freely to such other delivery, even if the same is located upon the opposite side of machine 10 or upon another spinning machine, since arm 30 is retracted and all components of the switching means of the present invention are then housed within the carriage of apparatus 12.

Restricting the performance of major yarn tensioning steps, such as recommencing bobbin rotation, to when the machine ring rail is adjacent the top of a reciprocatory stroke, is of course beneficial not only in piecing operations employing the yarn retrieval and/or other steps previously discussed herein. It may also be done in other piecings operations, such as one employing a seed yarn to re-establish the thread-line at a delivery undergoing servicing, and may be initiated either in immediate or in timed response to sensed ring rail position.

Since various other modifications and alternative embodiments of the invention will be apparent to those skilled in the art, it is to be understood that the disclosure herein of one specific embodiment has been for purposes of illustration only, and not for purposes of limitation, the scope of the invention being in accordance with the following claims.

That which is claimed is:

1. In the automatic end-down servicing of a textile spinning machine having a bobbin-yarn package encircled by a spinning ring carried by a ring rail vertically movable during operation of the spinning machine through reciprocatory traverses, each servicing operation including rotating the package in an unwinding direction while retrieving yarn from the package by yarn retrieving means movable vertically with the ring rail, the improvement comprising detecting reversals of the direction of movement of the ring rail of the spinning machine at opposite ends of reciprocatory traverses thereof, initiating the yarn retrieving step of each piecing operation in response to a detected reversal of the direction of movement of the ring rail from upwardly to downwardly, and terminating the yarn retrieving step of each piecing operation in response to a detected reversal of the direction of movement of the ring rail from downwardly to upwardly.

2. A method as in claim 1, wherein the step of retrieving yarn from the package includes applying a suction force to the surface of the package.

3. A method as in claim 1, wherein the step of retrieving yarn from the package includes applying a beating force to the surface of the package.

4. A method as in claim 1, wherein the step of retrieving yarn from the package includes applying suction and beating forces to a tapered chase surface of the package.

5. In the automatic end-down servicing of a textile spinning machine having a bobbin-yarn package encircled by a spinning ring carried by a ring rail vertically movable during operation of the spinning machine through reciprocatory traverses, each servicing operation including rotating the package in an unwinding direction while retrieving yarn from the package by yarn retrieving means movable vertically with ring rail, halting package rotation after retrieval of yarn from the package, interconnecting a length of the yarn retrieved from and connected to the package with a traveler movable about the spinning ring, extending the traveler-threaded yarn upwardly to an elevation adjacent drafting rolls of the spinning mashine, and thereafter performing at least one additional step tending to impose substanstial tension upon the traveler-threaded and upwardly-extended yarn, the improvement comprising: conducting substantially all of the step of retrieving yarn from the package, during each servicing operation, during downward movement only of the ring rail of the spinning machine; and thereafter performing said one additional step, tending to impose substantial tension upon the traveler-threaded and upwardlyextended yarn, only when the ring rail is adjacent the top of a reciprocatory traverse.

6. A method as in claim 5 wherein the one additional step is that of recommencing winding rotation of the package.

7. A method as in claim 5, including detecting reversal of the direction of movement of the ring rail at at least one end of a reciprocatory traverse diereof, and performing the additional step tending to tension the traveler-threaded yarn in response to detected reversal of movement of the ring rail.

8. A method as in claim 7, wherein the detected reversal of movement of the ring rail is from downwardly 14 to upwardly and the additional step tending to tension the traveler-threaded yarn is perfon'ned while the ring rail is moving upwardly.

9. A method as in claim 5, wherein each servicing operation includes a first additional step and a second additional step each tending to tension the travelerthreaded yarn and each performed only when the ring rail is adjacent the top of a reciprocatory traverse, the second step being preceded by the first step comprising recommencing winding rotation of the package.

10. In the automatic end-down servicing of a textile spinning machine including a bobbin encircled by a spinning ring having a traveler rotatable thereabout and carried by a ring rail vertically movable during the operation of the spinning machine through reciprocatory traverses, each servicing operation including establishing a traveler-threaded length of yarn connected at one end to the bobbin and extending at its upper end upwardly toward the elevation of drafting rolls of the spinning machine, and further including at least one additional step tending to impose substantial tension upon the traveler-threaded yarn, the improvement comprising performing said additional step during each servicing operation only when the ring rail of the spinning machine is adjacent the top of a reciprocatory traverse thereof.

11. A method as in claim 10, wherein all steps of each ser icing operation tending to impose substantial tension upon the traveler-threaded yarn are performed only when the ring rail is adjacent the top of a reciprocatory traverse thereof.

12. A method as in claim 10, wherein said additional step is that of recommencing winding rotation of the bobbin.

13. A method as in claim 10, including detecting reversal of the direction of movement of the ring rail at at least one end of a reciprocatory traverse thereof, and performing said additional step in response to detected reversal of movement of the ring rail.

14. A method as in claim 13, wherein the detected reversal of movement of the ring rail is from downwardly to upwardly, and said additional step is performed in timed response to said detected reversal of ring rail movement while the ring rail is moving upwardly.

15. in combination with an automatic yarn piecing apparatus servicing a textile spinning machine having a ring rail vertically movable through reciprocatory traverses during end-down servicing of said machine by said apparatus, said apparatus including control means for correlating the performance of at least one step of each servicing operation with the position of said ring rail of said spinning machine, the improvement comprising:

switching means forming part of said control means and including cooperating switch and switchactuating elements;

and means mounting said elements for vertical movement during at least part of each servicing operation in unison with each other and with said ring rail while said ring rail is moving through an intermediate part of a reciprocatory traverse thereof. and for movement of one of said elements relative to the other of said elements and to said ring rail upon reversal of the direction of movement of said ring rail at an end of a reciprocatory traverse of said ring rail, said switch element being actuable by said relative movement between said elements, said mounting means including an extendable and retractable support arm engaging and supported by said ring rail, during said part of each servicing operation, for free vertical movement in unison with said ring rail under the impetus of the movement of said ring rail.

16. Apparatus as in claim 15, wherein said mounting means includes a pair of elongate members carried by said piecing apparatus and respectively mounting said elements for independent vertical movement along adjacent paths of travel; and lost-motion interconnecting means interconnecting said elements for movement along said paths of travel substantially in unison with each other except upon reversal of the direction of movement thereof, and for then permitting relative movement between said elements.

17. Apparatus as in claim 16, wherein one of said elongate members is formed of magnetic material, and the one of said elements mounted by said one member is slidable longitudinally thereof subject to a magnetic drag-force thereon.

18. Apparatus as in claim 15, wherein said switchactuating element includes a cam block formed of wear-resistant plastic material and having a vertically sloping cam face thereon, and wherein said switch element includes a switch arm having a roller at its free end and biased into engagement with said cam face upon said cam block. 

1. In the automatic end-down servicing of a textile spinning machine having a bobbin-yarn package encircled by a spinning ring carried by a ring rail vertically movable during operation of the spinning machine through reciprocatory traverses, each servicing operation including rotating the package in an unwinding direction while retrieving yarn from the package by yarn retrieving means movable vertically with the ring rail, the improvement comprising detecting reversals of the direction of movement of the ring rail of the spinning machine at opposite ends of reciprocatory traverses thereof, initiating the yarn retrieving step of each piecing operation in response to a detected reversal of the direction of movement of the ring rail from upwardly to downwardly, and terminating the yarn retrieving step of each piecing operation in response to a detected reversal of the direction of movement of the ring rail from downwardly to upwardly.
 2. A method as in claim 1, wherein the step of retrieving yarn from the package includes applying a suction force to the surface of the package.
 3. A method as in claim 1, wherein the step of retrieving yarn from the package includes applying a beating force to the surface of the package.
 4. A method as in claim 1, wherein the step of retrieving yarn from the package includes applying suction and beating forces to a tapered chase surface of the package.
 5. In the automatic end-down servicing of a textile spinning machine having a bobbin-yarn package encircled by a spinning ring carried by a ring rail vertically movable during operation of the spinning machine through reciprocatory traverses, each servicing operation including rotating the package in an unwinding direction while retrieving yarn from the package by yarn retrieving means movable vertically with ring rail, halting package rotation after retrieval of yarn from the package, interconnecting a length of the yarn retrieved from and connected to the package with a traveler movable about the spinning ring, extending the traveler-threaded yarn upwardly to an elevation adjacent drafting rolls of the spinning mashine, and thereafter performing at least one additional step tending to impose substanstial tension upon the traveler-threaded and upwardly-extended yarn, the improvement comprising: conducting substantially all of the step of retrieving yarn from the package, during each servicing operation, during downward movement only of the ring rail of the spinning machine; and thereafter performing said one additional step, tending to impose substantial tension upon the traveler-threaded and upwardly-extended yarn, only when the ring rail is adjacent the top of a reciprocatory traverse.
 6. A method as in claim 5 wherein the one additional step is that of recommencing winding rotation of the package.
 7. A method as in claim 5, including detecting reversal of the direction of movement of the ring rail at at least one end of a reciprocatory traverse thereof, and performing the additional step tending to tension the traveler-threaded yarn in response to detected reversal of movement of the ring rail.
 8. A method as in claim 7, wherein the detected reversal of movement of the ring rail is from downwardly to upwardly and the additional step tending to tension the traveler-threaded yarn is performed while the ring rail is moving upwardly.
 9. A method as in claim 5, wherein each servicing operation includes a first additional step and a second additional step each tending to tension the traveler-threaded yarn and each performed only when the ring rail is adjacent the top of a reciprocatory traverse, the second step being preceded by the first step comprising recommencing winding rotation of the package.
 10. In the automatic end-down servicing of a textile spinning machine including a bobbin encircled by a spinning ring having a traveler rotatable thereabout and carried by a ring rail vertically movable during the operation of the spinning machine through reciprocatory tRaverses, each servicing operation including establishing a traveler-threaded length of yarn connected at one end to the bobbin and extending at its upper end upwardly toward the elevation of drafting rolls of the spinning machine, and further including at least one additional step tending to impose substantial tension upon the traveler-threaded yarn, the improvement comprising performing said additional step during each servicing operation only when the ring rail of the spinning machine is adjacent the top of a reciprocatory traverse thereof.
 11. A method as in claim 10, wherein all steps of each servicing operation tending to impose substantial tension upon the traveler-threaded yarn are performed only when the ring rail is adjacent the top of a reciprocatory traverse thereof.
 12. A method as in claim 10, wherein said additional step is that of recommencing winding rotation of the bobbin.
 13. A method as in claim 10, including detecting reversal of the direction of movement of the ring rail at at least one end of a reciprocatory traverse thereof, and performing said additional step in response to detected reversal of movement of the ring rail.
 14. A method as in claim 13, wherein the detected reversal of movement of the ring rail is from downwardly to upwardly, and said additional step is performed in timed response to said detected reversal of ring rail movement while the ring rail is moving upwardly.
 15. In combination with an automatic yarn piecing apparatus servicing a textile spinning machine having a ring rail vertically movable through reciprocatory traverses during end-down servicing of said machine by said apparatus, said apparatus including control means for correlating the performance of at least one step of each servicing operation with the position of said ring rail of said spinning machine, the improvement comprising: switching means forming part of said control means and including cooperating switch and switch-actuating elements; and means mounting said elements for vertical movement during at least part of each servicing operation in unison with each other and with said ring rail while said ring rail is moving through an intermediate part of a reciprocatory traverse thereof, and for movement of one of said elements relative to the other of said elements and to said ring rail upon reversal of the direction of movement of said ring rail at an end of a reciprocatory traverse of said ring rail, said switch element being actuable by said relative movement between said elements, said mounting means including an extendable and retractable support arm engaging and supported by said ring rail, during said part of each servicing operation, for free vertical movement in unison with said ring rail under the impetus of the movement of said ring rail.
 16. Apparatus as in claim 15, wherein said mounting means includes a pair of elongate members carried by said piecing apparatus and respectively mounting said elements for independent vertical movement along adjacent paths of travel; and lost-motion interconnecting means interconnecting said elements for movement along said paths of travel substantially in unison with each other except upon reversal of the direction of movement thereof, and for then permitting relative movement between said elements.
 17. Apparatus as in claim 16, wherein one of said elongate members is formed of magnetic material, and the one of said elements mounted by said one member is slidable longitudinally thereof subject to a magnetic drag-force thereon.
 18. Apparatus as in claim 15, wherein said switch-actuating element includes a cam block formed of wear-resistant plastic material and having a vertically sloping cam face thereon, and wherein said switch element includes a switch arm having a roller at its free end and biased into engagement with said cam face upon said cam block. 